Add program to the right-click menu can be more convenient

Directories are supported now.
Next step is to support right-click on multiple files.

Start by tracing the existing right-click handling for directories in the C++ project. Check how the Windows context-menu entry receives its target path, then determine how multiple selected files are represented. Done means the right-click action accepts and processes multiple files while preserving the existing directory behavior.

Written by the indexing model from the issue text.